chore: release v0.26.4

compact.go

@@ -0,0 +1,102 @@
+package main
+
+// Compacting a database.
+//
+// SQLite never shrinks a file on its own: deleting rows — or dropping a table,
+// which is what the schema-role cleanup does — frees pages INSIDE the file and
+// leaves the file the size it always was. A logbook that held 200 000 imported
+// QSOs for a day is still a 200 MB file the day after they are gone, and the
+// only thing that reclaims the space is a VACUUM, which rewrites the database
+// from scratch.
+//
+// Offered as a button rather than done automatically: a VACUUM rewrites the
+// whole file, needs room for a second copy of it while it runs, and takes real
+// time on a large logbook. That is a decision for the operator, at a moment they
+// choose — not something to spring on them during startup.
+
+import (
+	"database/sql"
+	"fmt"
+	"os"
+	"strings"
+
+	"hamlog/internal/applog"
+)
+
+// CompactResult is what one compaction did.
+type CompactResult struct {
+	// Path of the file compacted, empty for MySQL.
+	Path string `json:"path"`
+	// Backend is "sqlite" or "mysql" — a shared server is optimised, not vacuumed.
+	Backend string `json:"backend"`
+	// Before and After are file sizes in bytes; both 0 when there is no file.
+	Before int64 `json:"before"`
+	After  int64 `json:"after"`
+}
+
+// CompactDatabase reclaims the unused space in one of the two databases.
+//
+// target is "settings" or "logbook". They are separate on purpose: they are
+// different files, of very different sizes, and an operator compacting a 400 MB
+// logbook has no reason to wait on a 2 MB settings file as well.
+func (a *App) CompactDatabase(target string) (CompactResult, error) {
+	switch strings.ToLower(strings.TrimSpace(target)) {
+	case "settings":
+		if a.db == nil {
+			return CompactResult{}, fmt.Errorf("the settings database is not open")
+		}
+		return a.vacuumSQLite(a.db, a.dbPath)
+	case "logbook":
+		if a.logDb == nil {
+			return CompactResult{}, fmt.Errorf("the logbook is not open")
+		}
+		if a.dbBackend == "mysql" {
+			// A shared server's storage is the admin's business, and OPTIMIZE TABLE
+			// locks the table for the length of a rebuild — every other operator
+			// waits. Still offered, because a logbook that has had a large import
+			// deleted benefits from it just as much; it simply reports no sizes,
+			// which the server alone knows.
+			if _, err := a.logDb.ExecContext(a.ctx, "OPTIMIZE TABLE qso"); err != nil {
+				return CompactResult{}, fmt.Errorf("optimize qso: %w", err)
+			}
+			applog.Printf("compact: OPTIMIZE TABLE qso on the shared MySQL logbook")
+			return CompactResult{Backend: "mysql"}, nil
+		}
+		// No separate file: the settings database is serving as the logbook, and
+		// compacting it is the same operation.
+		if a.logDbPath == "" {
+			return a.vacuumSQLite(a.db, a.dbPath)
+		}
+		return a.vacuumSQLite(a.logDb, a.logDbPath)
+	}
+	return CompactResult{}, fmt.Errorf("unknown database %q", target)
+}
+
+// vacuumSQLite checkpoints the write-ahead log, then rewrites the file.
+func (a *App) vacuumSQLite(conn *sql.DB, path string) (CompactResult, error) {
+	res := CompactResult{Path: path, Backend: "sqlite", Before: fileSizeOf(path)}
+	// Fold the WAL back into the main file first. Without it the pages freed by a
+	// recent DELETE can still be sitting in the -wal, and the vacuum reports a
+	// saving the file on disk does not show.
+	if _, err := conn.ExecContext(a.ctx, "PRAGMA wal_checkpoint(TRUNCATE)"); err != nil {
+		applog.Printf("compact: wal checkpoint on %s: %v", path, err)
+	}
+	if _, err := conn.ExecContext(a.ctx, "VACUUM"); err != nil {
+		return res, fmt.Errorf("vacuum: %w", err)
+	}
+	res.After = fileSizeOf(path)
+	applog.Printf("compact: %s %d → %d bytes", path, res.Before, res.After)
+	return res, nil
+}
+
+// fileSizeOf returns a file's size, or 0 if it cannot be read.
+func fileSizeOf(path string) int64 {
+	if strings.TrimSpace(path) == "" {
+		return 0
+	}
+	fi, err := os.Stat(path)
+	if err != nil {
+		return 0
+	}
+	return fi.Size()
+}